SALT LAKE CITY — Investigators found child pornography on Josh Powell's computer at least 17 months before he killed his children and himself, according to FBI documents.

The Salt Lake Tribune reported Saturday that the documents show the FBI was investigating the disappearance of his wife, Susan Powell, as well as possession of child pornography.

Anne Bremner, an attorney for Susan Powell's parents, said the family was never told the FBI was investigating Josh Powell for child pornography. If the state of Washington's Department of Social and Health Services had known about the suspected child pornography, it "never would have let him have those kids," she said.

When a state worker delivered 7-year-old Charlie and 5-year-old Braden to Josh Powell's rented home in Graham, Washington, on Feb. 5, 2012, Josh Powell locked out the worker and ignited a fire that killed him and his sons.

Susan Powell, who was last seen at her West Valley City, Utah, home on Dec. 6, 2009, has never been found.

Josh Powell had been previously linked to child pornography, the Tribune reported. At hearings in the state of Washington to determine custody of his children, then-Assistant Washington Attorney General John M. Long said Powell was under investigation for child pornography after cartoon images of incest between mothers and children were found on his computer in late 2009 or early 2010.